Manhole construction



Feb. 17, 1931. L. G. ZIMMERMANN 1,793,038

MANHOLE CONSTRUCTION Filed March 7, 1928 2 Sheets-Sheet l LIT gull Z6 IA,

INVEN TOR.

BYQZKVKW M M M21 221 A TTORNEYS.

Feb. 17, 1931. G. ZIMMERMANN 1,793,038

MANHOLE CONSTRUCTION Filed March 7, 1928 2 Sheets-Sheet 2 INVEN TOR.

- A TTORNEYS Patented Feb. 17, 1931 PATENT OFFICE LEROY G. ZIMMERMANN,OF MILWAUKEE, WISCONSIN V MANHOLE CONSTRUCTION Application filed March7,

This invention relates to improvements in manhole constructions.

It is the object of the invention to provide a manhole casing adaptedfor factory manufacture and assembly and standardized units in thelocation and to the required depth of manhole.

Further objects of the invention relate to a novel top section unitadapted to receive a standard cover, and to a floating cover ringmounted on such unit and provided with centering means whereby it neednot be secured to the aforesaid top manhole unit and may be heaved byfrost independently of such unit without disturbing the proper relationof the parts.

In the drawings Figure 1 is a side elevation in perspective of a deviceembodying this invention, fragments thereof being broken away;

Figure 2 is a detail View in vertical section' of the upper end of acasing device embodying this invention Figure 3 is a detail intransverse section taken in the plane indicated in 3-3 in Fig. 1;

Figure 4 is a side elevation of the bottom of the device;

Figure 5 is a detail view in plan of a fragment of one of the steps;

Figure 6 is a view of the step in transverse vertical section;

Figure 7 is a plan view of the device shown in Fig. 1;

Figure 8 is a section in the plane indicated at 8-8 in Figure 1.

Like parts are identified by similar reference numerals throughout theseveral views.

Only three principal types of castings are used to construct manholecasings in accordance with this invention. The fact that the number islimited to three effects great economies in manufacture and enablesproduction methods to be employed for the first time in this industry.

The base section 10 is provided upon two 1928. Serial No. 259,890.

diameters with downwardly opening notches in its opposite margins, asshown at 11 and 12. Notches 11 are semicircular and of relatively largedimensions to take pipe of the relative size indicated at 13. Notches 12are relatively smaller to receive pipes 14 which are laterals ordelivery pipes or may comprise the main. It is intended, however, thatpipe 13 shall represent the trunk line sewer and pipe 14 the laterals.

Upon the base 10 are assembled the annular sections 15 in verticalseries to any desired height. The base section 10 at each of theintermediate sections 15 is provided with a belled top flange 16 intowhich the bottom margin of the next succeeding section is receivable,the joint being filled with cement, as at 17 It is obvious that acompletely tight casing will result.

At the top of the series of intermediate sections 15, I employ anupwardly tapering top section 21 which is so formed as to eX- tendalmost vertically at the side 22 and to have a pronouncedly inclinedwall at 18. The vertical wall at 22 makes the ladder, hereinafter to bedescribed, more readily accessible. The cover ring 19 has wedge-shapedcentering lugs 20 at intervals about its under surface, such lugs beingso disposed as to fit about the open mouth of the top section 21 toposition or center the finishing plate 19 with respect to the opening.

In order that branch pipes or laterals may be introduced at a variety ofangles to the interior of the manhole casing at any desired elevation,it is preferred to provide each of the several intermediate sections 15of the casing with potential openings through which the lateral drainsmay extend. To this end each such intermediate section is provided at aplurality of points (preferably 4.) with round areas 25 of reducedthickness, such areas being bounded by beads 26 of increased thickness.As a result of this construction, it is readily possible to hammer orchisel out 90 the cast iron area of reduced thickness thereb lGELVlII an0 enin of a sue to receive a b D lateral pipe. The fact that eachsection is rovided with a number of such potential P l openings and thatthereare a number of secceive the correspondingly tapered pin portions29 of the steps 30. The sections 15 will be so assembled that the lugsQS t-hereof will be in vertical alignment whereby complete ladder may beformed by the simple expedient of inserting the several step elementsinto their respective lugs insuperposed relation.

In constructing amanhole casing embodying this invention, the bottomsection 10 is laid upon the completed length of pipe 13 which extendstherebeneath. The .pipe will be received into the notchesll and 12, ac-

cording to the angular position of the manhole, and, as above indicated,is preferably received into notches 11. The bottom section is thus sopositioned as to straddle the pipe.

Concrete mix will now be poured around the pipe within and about thebottom section 10 of the manhole casing. The concrete will fill'thebottom of the excavation at least to a depth sufficient to reach thelower margin of the section 10. This will imlced approximately half ofthe pipe 13 in the concrete foundation. Thereafter, at any subsequenttime, the top of pipe 13 is broken in bya sledge or with a chiseltoprovide an opening 300 for communication between the'in terior of themanhole and the interior of the pipe. f

The several sections 15 are now laid up, one upon another, the jointsbetween them being cemented, as above indicated, and at the proper pointthe top section 22 is set in place. In laying up the sections 15 theweakened areas will be broken out and lateral drains introduced as maybe required. The excavation about the manhole casing is now filled withearth and the finishing ring '19 is laid to cover the upper margin ofthe top 22 and to receive the manhole cover 32. One of the difficultiesheretofore experienced in the use of top plates or finishing plates hasbeen the fact that they afforded a horizontal surface against which thesurrounding earth could exert pressure in expanding or heaving under theinfluence of frost. With a top plate manufactured in accordance withthis invention, no difficulty is experienced due to the fact that thetop plate is floating and selfcentering so that when the earth againcontracts, the top plate will settle back into a properly centeredposition at the upper margin of section 21 of the manholecasing.

It will be observed that the majority of the parts entering into theconstruction of this ever, that so far as oversized laterals areconcerned it is possible if desired to divide the lateral and bring itinto the manhole casing through two or more of the openings alreadyprovided for. r

It is possible, therefore, to manufacture cast iron manhole casings byproduction methods at prices sufliciently low to compete withjtheinferiorv masonry constructions" heretofore employed. g

It will be understood, of course, that the shape of such casings is notspecifically material. will necessarily be annular in the sense thateachunit will comprise a closed geometrical figure whenviewed in plan,or in other words, will have a continuous peripheral wall. This does notmean, however, that the casing must necessarily be round as illustratedalthough the round construction is to be preferred be causeof-convenience and economy, Neither is it essential that the individualsections should maintain the illustrated ratio of diameter to axialextent, but hereagain it is preferred that the sectionsshould berelatively fiat in order that they may not be too weighty and difficultto manufacture and handle. The diameter is preferably relatively largeto give the desired size of manhole, while the axial extent is small inorder that the units may convenientlybe assembled with small incrementsof change to any desired structural height in order to meet exist- Eachunit entering into the casing ing requirements at the place ofinstallation. 7

I claim: 1. In a device of the character. described, the combinationwith a casing member having a well defined upper margin, of anoverformed to center said plate with reference to said inarginupon theoccurrence of relasaid plate having radially disposed lugs nor-.

mally supporting its overhanging portion from the tapering surface ofsaid member and adapted to center said plate with respect to said memberupon the occurrence of relative vertical movement with respect thereto.

LEROY G. ZIMMERMANN.

